Experiments evaluating factors which alter the metabolism of fibrinogen will be performed and the effects of arvin, exogenous fibrinogen, and fibrinogen-fibrin degradation products (FDP-fdp) on fibrinogen metabolism measured. The model (in rabbits) will allow discrimination between changes in synthesis, catabolism, or extravascular pools. The use of blood, defibrinogenated by arvin, will be evaluated as a perfusate for explanted human kidneys preserved for transplantation. Studies employing arvin to prevent post-operative, intraperitoneal visceral adhesions and fibrosis in dogs will be performed. Studies of prothrombin metabolism will be carried out in man, during defibrinogenation by arvin. An attempt will be made to determine the site at which cyanate inhibits the clottability of fibrinogen, and whether the enzymatic or polymerization step in the conversion of fibrinogen to fibrin is blocked. Stable, biologically active bacterial endotoxin will be radioactively labeled and used to evaluate the mechanisms by which endotoxins exert various pathophysiological effects, and to provide another approach to the fractionation of lysates prepared from the amebocytes of Limulus polyphemus (the horseshoe crab). Further purification of the clottable protein of Limulus blood will be attempted. Electron microscopic studies of the endothelium of small blood vessels, following the induction of thrombocytopenia in rabbits, will be performed. The use of heparin for the treatment of disseminated intravascular coagulation will be evaluated in a controlled, double-blind study. The incidence of thrombocytopenia in patients receiving heparin will be studied. The relative efficacies of urinary urokinase and tissue culture urokinase, for the treatment of pulmonary embolism in man, will be evaluated.